Radiators on upper floors are cold while lower floors heat normally.

Safety: Allow system to cool slightly before bleeding radiators.

• Increase system pressure: Top up to the upper end of Kospel's recommended cold pressure range to help push air out.
• Bleed upper radiators: Use a radiator key to release air until water flows steadily.
• Check pump speed: Set the circulation pump to a higher speed if available.
• Open balancing valves: Ensure valves on risers and upper circuits are fully open.